An engine circulates oil for lubricating and cooling several parts thereof. The oil is stored in an oil pan and is fed into an oil subgallery by an oil pump. The oil in the oil subgallery is fed through an oil filter so as to remove foreign matter, and thereafter is fed into an oil main gallery in order to lubricate and cool parts of the engine.
FIG. 7 shows such a conventional oil filter attaching structure for an engine without an oil cooler. Arrows in FIG. 7 indicate the direction of oil flow.
Referring to FIG. 7, there is shown part of a lower casing 202 for an engine without an oil cooler. This lower casing 202 is provided with a casing-side journal member 204 for journalling a crankshaft (not shown) in cooperation with a block-side journal part (not shown). Each end of the casing-side journal member 204, which extends in a direction transverse to a crankshaft axis A, is coupled to a casing-side coupling member 206.
In the lower casing 202, the casing-side coupling member 206 is formed with a subgallery 208 into which oil is fed from an oil pump (not shown), and is also formed with a main gallery 210 for feeding filtered oil from 35 which particulates are removed, into various parts of the engine.
The coupling member 206 of the lower casing 202 is formed with a stand hole 212 which communicates with the main gallery 210. The stand hole 212 for engines without an oil cooler, is formed with a female thread part 214 having a length extending upwardly beyond the main gallery 210. A filter stand 216 for use on engines without an oil cooler is provided. A male thread part 218 is provided at one end of the filter stand 216. The male thread part 218 is screwed into the female thread part 214 of the hole 212. The male thread part 218 has a longitudinal length which is set so as to prevent the main gallery 210 from being blocked.
The filter stand 216 as screwed in the stand hole 212 has a filter male thread part 222 which is provided on the other end thereof, and onto which an oil filter 224 is screwed. An intermediate non-thread part 220 is located on filter stand 216 between the male thread parts 218 and 222. The oil filter 224 communicates with the subgallery 208 through a filter introduction hole 226 formed in the casing 202, and also communicates with the stand hole 212 through a stand oil passage 228 which extends through the stand 216 so as to allow oil to flow from the oil filter into the main gallery 210.
Referring now to FIG. 8, a conventional oil filter attaching structure for an engine with an oil cooler is shown. Arrows in FIG. 8 indicate the direction of oil flow. In FIG. 8, a casing-side journal member 304 is formed in lower casing 302 and a coupling member 306 is formed with a stand hole 312 which communicates with a main gallery 310. This stand hole 312 is formed with a female thread part 314 having a length extending upwardly beyond the main gallery 310. A filter stand 316 for use on engines with an oil cooler is provided. A male thread part 318 is located on one end of the filter stand 316 and screws into the female thread part 314. The male thread part 318 has a longitudinal length which is set so that it blocks the main gallery 310 to prevent direct communication with the stand hole 312.
The filter stand 316 when screwed in the stand hole 312 has the male thread part 318 blocking the main gallery 310, and a filter male thread part 322 which is provided on the other end. An intermediate non-thread part 320 is located between the male thread parts 318 and 322. The filter male thread part 322 has screwed thereon an oil filter 324. The oil filter 324 communicates with a subgallery 308 through a filter introduction hole 326, and also communicates with the stand hole 312 through a stand oil passage 328 in the filter stand 316.
Further, in the lower casing 302, the casing-side coupling member 306 is formed with a cooler bolt hole 330 communicating with the main gallery 310 and inclined with respect to the stand hole 312. The cooler bolt hole 330 has formed therein a cooler female thread part 332. A bolt male thread part 336 of a cooler bolt 334 is screwed into the cooler female thread part 332. Thereby, oil cooler 338 is mounted to the coupling member 306.
The oil cooler 338 communicates with the stand hole 312 through a cooler introduction hole 340 formed in the casing 302, and communicates with the main gallery 310 through a bolt oil passage 342 formed in the cooler bolt 334.
The male thread part 318 has a length which is set so that it blocks the main gallery 310, and accordingly, oil having passed through the oil filter 324 flows through the oil cooler 334 without flowing directly into the main gallery 310.
The stand hole 212 in the conventional lower casing 202 of FIG. 7 is formed with the female thread part 214 having a length extending beyond the main gallery 210. Similarly, the female thread part 314 in the stand hole 312 of the conventional lower casing 302 of FIG. 8 is also formed with the female thread part 314 having a length extending beyond the main gallery 310.
Referring to FIG. 9, a possible engine assembly line problem is illustrated if the wrong filter stand is selected during engine assembly. In FIG. 9 the male thread part 318 of the filter stand 316 (for use with an oil cooler) is screwed, in error, into the female thread part 214 of the lower casing 202 (for use without an oil cooler), causing a defective assembly. In the case of this defective assembly, the male thread part 318, due to its length, blocks the main gallery 210, and accordingly oil cannot flow into the main gallery 210, causing possible engine damage or seizure. In FIG. 9, it can be sen that after the improper assembly, the only part of filter stand 316 that is visible is the thread part 322 and the non-thread part 320. Visually, this is substantially identical to the proper assemblies shown in FIGS. 7 and 8, and thus it is not possible to visually discriminate between a correct and an incorrect assembly.